Shingeki no Kaiju
by Exantis
Summary: Crossover between Attack on Titan and Pacific Rim. The secret in Eren's basement has been discovered. It leads to a portal to another world. From the other side comes giant monsters and giant robots. Now as the humans from two different worlds meet, two civilizations will merge. But two threats will merge too.
1. To You, 2000 Tons From Above

**Author's Notes: **It has always been a topic for discussion among my friends how Attack on Titan is so similar to Pacific Rim. This is my interpretation of how the two stories will come together. The timeline at the start of this story is from Attack on Titan chapter 51 onwards and towards the end of Pacific Rim, just moments before Gipsy and Striker attack the Breach. This is also presuming that Striker Eureka was not destroyed. Also Cherno Alpha's and Crimson Typhoon's crews are still alive.

* * *

"So this is it?" Commander Pixis asked

"Yes, this is the Forbidden Gateway," Historia answered, her small frame dwarfed by the gigantic gate in front of them. "The origin of the Titans is beyond here."

Historia stood in awe at the head of the hastily assembled combined forces of the Scouting Legion, the Garrison and the Military Police.

Her family had always stressed the significance of the Forbidden Gateway, but never in her wildest imagination would she have visualized such a magnificent piece of engineering. Who would have ever thought that the key to ending the entire Titan War was to be found in the thickest portion of Wall Rose? A gate of reinforced metal never before seen in the world, inscribed with ancient texts of warning.

Such a structure called for great attention. Even after the high mortality rate the Scouting Legion suffered from rescuing her, they were only further spurred to discover what was in the basement of Eren's house. A last-ditch effort was made and the Legion committed its entire force in a blitzkrieg towards Shiganshina District. Their retrieval mission cost them dearly, now only 34 members of the Legion remained.

But all they discovered in the basement was a key. One that Historia had been charged to find since birth.

Now all the sacrifices humanity has made over the past 5 years have culminated in this one moment.

Historia looked back. Every eye was on her, every hand was on their blade, ready to leap into high-speed combat at any moment. Her comrades from what remained of the former 104th Trainee Squad stood at her back. Jean, Connie, Sasha, Armin, Mikasa and most importantly Eren. The anxiety in their eyes made her shiver. Eren was especially nervous. His father had left this world to travel beyond this very gate.

"I'm opening the gate now." She announced.

A flurry of sharp movements erupted behind her as every single soldier readied cannon, rifle and 3D Gear.

She inserted the silver key into an oddly-shaped hole which was most likely the keyhole.

There was a loud hiss, steam bellowed from vents in the side of the gate. The massive block of metal was slowly lifted into the air by old pulleys. Bright sparks of energy rippled over the surface behind the gate. A freezing gust of air blew through the small opening, bathing everyone in an ice-cold spray of water.

No one was prepared for the sight they would see.

A sea.

"A-Armin," Eren nudged his friend "Remember the time you were talking about the outside world? About how the world was covered by the sea?"

The frail boy nodded, his mouth gaped at the spectacular sight before them.

Their dreams had finally come true. A vast expanse of water lay before them, just beyond the gate. The outside world was never beyond the walls, but within them.

Even Commander Pixis was staring in amazement with Commander Erwin beside him.

"T-this is incredible."

Then the grandeur of the sea was cut short.

"Movement in the water!"

Everyone suddenly sprung into combat stance. A massive ripple of water the size of a house was moving towards them at a lightning-fast rate. Water was thrown into the air as a massive beast emerged from the water, crashing through the gate like it was paper. Flashbacks of the horrors from when the Colossal Titan first blew a hole in the walls struck everyone.

With a deafening roar, the beast announced itself. It stood as tall as the wall itself. Similar to a bull in form, it stood on its hind legs. Tough grey armor plating covered its scaly body. Orange stripes streaked across reptilian-like skin. A massive forked tail swept over the heads of the stunned humans. It had four menacing eyes, two on each side of its head, staring down upon the tiny humans. It was bleeding a strange luminescent blue blood. It poised its human-like arms with huge claws for fingers.

The Colossal Titan would be considered short in comparison to this beast.

This was true monster.

After a brief exchange of curious glances, the beast let out another roar and brought its massive hands up, preparing to attack.

"ALL UNITS, ATTACK!"

Levi's squad charged into action first. They fired their grappling hooks at the skin of the beast, blasting themselves towards its head as cannon fire whipped overhead. The shots did no damage and only irritated the beast more. It placed a massive foot forward and crushed the cannon batteries in a single stomp.

The hooks of the 3D Gear suddenly lost their grip as the muscles of the beast moved. Everyone attached to it lost their grip and fell.

But Mikasa was the first to recover. She twirled in the air and fired another hook at the beast's arm. Yelling her battle cry, she slashed at the beast. She however, did not expect her blades to break. The steel shattered upon the armor plating. The force shoved her backwards and she tumbled through the air.

"Mikasa!" Eren yelled.

He diverted from his attack to save her.

Levi was next to line himself up for an attack. He shot his hands to the right, creating momentum for his signature spinning attack. His attack drew blood. Yet the armor of the beast was too tough and his blades broke too. For the first time, the legendary Levi was spinning out of control as his attack was shrugged off.

Pixis and Erwin watched from afar.

"There's no way we can harm that beast!" Erwin cried.

"We can't retreat now! Continue the attack!"  
Pixis was out of his mind. But there was no retreat for them. This one beast alone could do a hundred times more damage than all the Titan attacks combined.

To their horror, another ripple of water was forming behind the beast.

This time however, a loud horn marked the arrival of a second beast. Bright lights broke the surface and a huge figure stood up. A huge metal Titan had arrived.

It had a single eye in a "W" shape, made of tessellated yellow glass. The Titan had a crude painting of a scantily-clad woman on its right breastplate and it stood like an arrogant Military Police soldier. It too was badly damaged, metal supports showing beneath crushed plates of armor.

Eren and Mikasa were on the ground just a few hundred meters from it. Mikasa recalled how she had first seen Eren as a Titan when she had almost given up all hope of living. She grabbed his arm as she realized this time there was no friend in that Titan.

"ALL UNITS, FALL BACK!" Pixis bellowed.

Mikasa and Eren were too far. They held onto each other and prepared themselves for the end.

The Metal Titan unexpectedly raised its fist. The first beast turned its head towards the newcomer. The fist of the Metal Titan went soaring through the air and into the face of the beast, a trail of fire behind its elbow.

The beast roared in pain.

It had no time to rest as the Metal Titan's hand morphed into a cannon spewing a strange blue energy. 3 sharp cracks followed as balls of blue fire burned through the chest of the beast. The angry beast grabbed hold of the cannon and used its other hand to pierce into the side of the Metal Titan.

The Metal Titan retaliated as out from its other hand came a modular blade that emanated a low buzzing sound. It rammed the blade into the skull of the beast as both fell to the ground.

Mikasa grabbed Eren and sped away just as the beast and the Titan hit the ground. The sheer force of the impact blew them out of the air. The two were hurled onto a relatively flat piece of land, tumbling upon impact. A huge cloud of dust was kicked up.

When it subsided, Eren was lying face-flat on the ground. Mikasa picked him up.  
"Eren! Eren, are you injured?"

"No, I'm fine. What about the others?"

Mikasa scanned the area.

The Metal Titan and the beast were laying side-by-side, blue blood oozing from the beast's head, burning the ground where it flowed. Both of them lay absolutely still.

The remaining soldiers were picking themselves up. But a squad of Military Police soldiers and Commander Pixis were riding towards the two corpses.

Jean landed beside Pixis and Erwin.

"Alright, the Titans are down, now let's go finish them!"

Jean's leader instincts kicked in and he rallied some soldiers and they used their 3D gear to land on the Metal Titan, as the beast was clearly dead. He was just about to wind himself up for an attack on the Metal Titan's neck when he heard a faint voice coming from its eye.

_Marco. Marco_

Jean was stunned. He turned his gaze to the source of the voice

"Jean, what gives?" Connie landed beside him

"I… I thought I heard someone call out for Marco."

"But Marco is dead-"

The voice was heard again.

Both soldiers looked at each other. They wasted no time in heading towards the voice.

They fired their gears beside the eye of the Titan.

Two shadowy figures were beside the broken glass eye. One was kneeling and holding the other's body up. They had a strange head, clad in black armor with a silver spine protruding from their backs.

Jean and Connie approached slowly, swords ready to cut down the strange figures should they be hostile. The one kneeling placed down the body and took of its head, revealing a human head underneath. A man with blonde hair removed the head of the other to reveal a young woman with black hair, partially dyed with blue on both sides of her hair.

"A human?!" Jean couldn't believe his eyes

He recalled how Eren had emerged from the back of the Titan, as did Annie. He gripped his swords tighter. But Connie grabbed his arm.

"Jean wait."

The blonde man spoke in the same voice they had heard earlier.

"Mako! Mako!"

The woman coughed as she came back to life.

"I'm alright, Raleigh."

She giggled a bit before embracing the man.

Now Jean was confused. So the man was calling out for his partner and not Marco.

The two Scouting Legion soldiers lowered their weapons and approached the two. At first the two reeled back into a defensive stance, but when they saw human faces, they lowered their guard, albeit perplexed as if they've seen a ghost.

There was an awkward pause as both sides tried to comprehend the fact that there were humans beyond their world.

Finally, the blonde man spoke into his helmet.

"LOCCENT… we have _human_ contact in the Breach."


	2. The Jaeger and The Truth

Stacker Pentacost squinted his eyes as the blinding flare of the setting sun appeared above the horizon, reflecting off the smooth texture of his Drivesuit. He shielded his eyes using his armored hand. This was definitely not what he had expected to be beyond the Breach. Rather, this was not the universe that the Kaiju came from. Yet according to Dr Gottlieb and Dr Geiszler readings, they were beyond the Breach.

"So where exactly are we, Dr Sarajevo?" The Marshal inquired.

Dr Grisham Sarajevo was an elderly man with long black hair, styled to a center-parting. He wore PPDC standard-issue HAZop gear, consisting of a specially made fiber uniform with a composite-kevlar flak jacket over it. But unlike his escort of 5 Shock Troopers, he wore no gas mask. Even though the air outside was safe, it was standard procedure to don full HAZop gear when entering unknown territory, just in case.

"The third dimension of the Breach, Marshal." The man had his eyes fixated on the gigantic wall below the helicopter, unmoved by the spectacular sight "Apparently, we were wrong. The Breach had three planes instead of two. I told you it was possible…"

The Marshal did not like the man's tone. He was unlike most other scientists with regards to research. While many would jump at the chance of a new discovery, Dr Sarajevo acted as if he knew everything. Despite his arrogance though, this man was truly a genius. In fact, you could say he laid the concept of the Jaeger program before Dr Schnoefeld and Dr Lightcap even pitched to idea to the United Nations. His idea provided the foundation for the two to come up with the Jaegers, whether or not the rest of the world would acknowledge it or not.

"Five minutes to DZ, Marshal!" The pilot announced over the radio.

By now, 3 hours had passed since Gipsy Danger reported human contact to LOCCENT. The QRF were scrambled into the new above-water Breach that opened. After confirming the safety of both pilots, they then turned their efforts towards establishing first-contact with the new humans. The United Nations were baffled by the Marshal's discovery. They seemed peaceful enough, so a PPDC expeditionary force was sent in to establish a forward base. Now it was Stacker's job to represent Earth to formally meet these new humans.

Dusk had descended upon them. Floodlights powered by mobile generators provided sufficient illumination for the base, much to the amazement of the backwards gas-lit lamps these humans had. Gipsy herself was parked next to the gigantic wall, kneeling beside the gate, repair crews desperately trying to fix whatever they could.

Four lights marked the makeshift-landing pad the expedition erected, just several hundred meters from the King's Palace.

As the Sea Dragon helicopter touched down, Stacker was greeted by a formation of soldiers in brown uniforms. There was also an elderly gentleman dressed in extravagant robes, whom he presumed was the king. They saluted him sharply with fists to their hearts.

The Marshal disembarked from the helicopter and returned the salute with a standard military one.

"Welcome to our kingdom Outlander." The King offered his hand.

"It's a pleasure to meet you. I am Marshal Stacker Pentacost,"

Even with the Drivesuit on, Pentacost could feel the hesitance of the man. It was to be expected though. Meeting humans beyond your known universe is bewildering. Yet there was something more to it, something sinister… After a brief pause, the Marshal turned to introduce Sarajevo

"And this is Dr. Saraje-" The scientist was not behind him.

Pentacost gestured to one of the Shock Troopers, who came running at double-time.

"Where is Dr Sarajevo?"

"He left the chopper in a hurry when we touched down, sir."

"Damn, why didn't you stop him? Find him and tell him to meet us at Gipsy Danger ASAP."

"Yes sir!"

The Marshal apologized to the King for the awkwardness, then waved for his PPDC escort to follow him as they marched towards the Jaeger.

The Scouting Legion members were present there in ceremonial formation. Raleigh and Mako stood a little further from them. All of them were dwarfed by the massive machine.

"This is an amazing contraption!" The King exclaimed "T-this will surely help us turn the tide against the Titans!"

The stroll had given enough time for the King to explain the dire situation they were in, about the Titan War. The two human races finally found something in common. They were in a war against monsters larger than all of them. For the first time, the humans of this world beheld hope for them encased in a giant machine.

"What is the name of this weapon?"

"A Jaeger." Another voice answered from behind Gipsy Danger's leg.

All eyes were upon the mysterious man. Pentacost recognized him though.

"Ah, Dr Sarajev-"

"DAD!" Eren's voice resonated through the whole valley.

All the humans of this world broke formation and gasped at the sudden appearance of a long lost hero. Eren and Mikasa were the most shocked of them all. The atmosphere suddenly changed to celebration.

"DR JAEGER, YOU ARE ALIVE!"

Pentacost stood bewildered. So did every member of the PPDC present. The man he knew as Grisham Sarajevo was suddenly surrounded by the humans of this world as if they knew him.

Eren and Mikasa were the first to greet their father. Eren hugged his father tight, tears flowing from his eyes, bringing a tearing Mikasa into it as well. Armin was close by, as was Commander Pixis.

"Dr Jaeger… It's been too long. Where have you been?" Commander Erwin broke through the crowd using his remaining hand.

"It is a long story." Grisha turned towards Pentacost "Marshal, I believe I owe you, no, the whole Earth, an explanation."

He placed his hands on Eren's shoulders and smiled to his son. He saw a maturity in the boy's eyes, changed by his experiences. It was time he knew the truth of why he was burdened with Titan-Shifting powers.

"Listen everyone, I left you all to go to the other world before Wall Maria fell. But it was not because I abandoned you all to die. It was to perfect these weapons," He pointed towards Gipsy Danger "This is a Jaeger, the ultimate weapon to defeat the monsters that plague their world. The other side was driven by desperation to fight back against the Kaiju, beasts a thousand times more dangerous than a Titan."

Pentacost fit together the pieces of the puzzle quickly. Grisham Sarajevo suddenly appeared out of nowhere and gave the idea of giant machines to the United Nations, but in truth he crossed over from another dimension where Titans were plaguing humanity just as the Kaiju were. Then it was discovered in that world that a boy named Eren had the power to transform into a Titan. Which meant that…

"You mean-"

"Yes, Marshal. My son, Eren Jaeger, is the _original _Jaeger Program."

Eren glanced at his father in shock.

"There's more," Dr Jaeger's voice suddenly turned dull. There was a bitter taste at the tip of his tongue. "The Titans… We created the Titans to protect humanity."

All jubilee suddenly faded away. The smiles on everyone's faces turned into frowns. An eerie silence loomed over them.

"W-what are you saying, dad?" Eren's voice was meek. He threw off his father's grasp violently "WHAT DO YOU MEAN BY THAT?!"

The rage within everyone exploded. The Scouting Legion and Military Police raised their weapons at Dr Jaeger, fingers on gun triggers and 3D Gear blades. The PPDC soldiers raised their weapons against the other humans. Raleigh instinctively stepped in front of the Doctor to shield him.

"THAT IS BULLSHIT! HOW CAN TITANS BE PROTECTING US?!"

"THEY KILLED THOUSANDS OF HUMANS!"

"ARE YOU SAYING THAT WE WERE YOUR PLAY-THINGS?!"

"Don't you remember they killed mother?!" The rage within Eren's eyes burned hotter than the sun

"Listen to me!" Dr Jaeger placed a hand on Raleigh assuring him that he had control of the situation "What do you think is outside the walls? The answer is NOTHING! There is something far worse than Titans outside those walls! It is something that consumes worlds, leaving nothing but ash in its wake!"

Suddenly a horseman came riding towards them at full speed.

"Titans spotted outside Wall Rose!"

Grisha ignored the warning. His eyes were still fixated on everyone else.

Then there was a thunderous roar, followed by another coming from the great mountain range beyond Wall Maria. To the ears of the PPDC personal, it was an all too familiar sound. Pentacost was already paging LOCCENT urgently.

"That is the _real_ danger beyond our walls."

"KAIJU INCOMING!"


End file.
